The present invention relates to novel prostaglandin analogs. Particularly, the invention relates to prostaglandin analogs wherein the C-19 position is substituted by oxo, i.e., 19-keto-PG compounds or 19-oxo-PG compounds. Most particularly, the present invention relates to novel 13,14-dihydro-inter-oxa-19-oxo-PGE.sub.1 compounds, a disclosure of the preparation and pharmacological use of which is incorporated here by reference from U.S. Pat. No. 4,228,104.